Opteron 6300 Series Launch: An Incremental Upgrade on an Outdated Platform

Today marks the introduction of AMDs Opteron 6300 line of server processors, codenamed Abu Dhabi, based on the Piledriver core architecture. The new CPUs are poised to replace the Opteron 6200 series, codenamed Interlagos, based on last year’s Bulldozer architecture. The Piledriver cores deliver a slight performance increase and allow for a modest increase in clock rate.

With the manufacturing process unchanged at 32nm SOI at GLOBALFOUNDRIES’ Fab 1 in Dresden and no change in core-count or amount of cache, the Opteron 6300 series is an evolutionary improvement. The chip package consists of two dies forming a MCM (Multi-chip module). Each die features 4 modules including 2 ALUs and 1 FPU each, which amounts to 8 cores in AMD nomenclature.

Now some of the models come with less than 8 cores per module as there are variants with only 12, 8 and even 4 cores (yes that means only one active module per die). These SKUs are either based off partially defective dies, that didn’t meet the quality criteria on every module or are simply healthy die with the additional cores fused off. There are models ranging from 85W to 140W, with most are specc’ed at a 115W TDP. Compared to the desktop chips, AMD had to reduce clock rates a bit to hit the TDP targets with twice the number of cores. The full list of launch SKUs can be found in their press release. Most interestingly, not all of the models mentioned in the press release made it to AMD’s processor database.

The platform remains unchanged as well. The CPUs drop into the existing socket G34, which is an LGA design featuring 1974 contacts (the CPUs themselves only use 1944 of those). These are needed to support up to four DDR3 memory channels ? two per CPU die on the package. While this doesn’t change much, it allows existing servers to be upgraded with the new chips with a simple drop in CPU replacement, provided the vendor releases a BIOS upgrade. AMD used to tout this feature with their Opteron line again and again ever since it’s launch. It’s something rarely seen with competing products from Intel.

Regarding the platform, it should be noted that AMD didn’t bother to update their chipset accompanying their server CPUs for quite some time now. The server chipsets SR5650, SR5670 and SR5690 and the paired SP5100 southbridge were launched back in 2009. The southbridge is the server version of the SB700 series, which was actually launched in 2008. The northbridge is based on the 800 series chipset series, which itself was only a slightly updated 700 series chipset. AMD retrofitted these with some server features. On a 2012 platform we consider PCIe 2.0, SATA 3Gb/s and USB 2.0 an outdated feature set at the very least.

In their press release AMD cites a 24% performance increase over the previous Opteron 6200 generation in the SPECjbb2005 benchmark, which evaluates server performance with Java applications. Furthermore, AMD claims up to 40% increased performance per watt. These should be considered optimal cases, the average improvement will be a bit lower. Nevertheless, the new CPUs can be considered a straight upgrade with no downsides compared to the previous generation. Now, comparison with the competition is yet another story, that is beyond this article.

The Opteron 6300 series target 2-way or 4-way servers. AMD also announced that the Opteron 4300 series (Seoul) for 2-way and 3300 series (Delhi) for 1-way servers will launch in December. These are based on single dies with up to four modules which makes them more cost efficient.